Spray paving coating and method

ABSTRACT

A paving mixture for application to a surface and a method for the same. The mixture comprises a binding material layer applied to the surface to form a base layer on the surface, and an aggregate material layer applied on top of the binding material layer, wherein the binding material layer comprises at least 15% of the bitumen in the paving mixture by weight, the aggregate material layer contains an asphalt mixture that provides a road surface. The aggregate material layer and the binding material layer are combined on the surface within 30 seconds of application of the binding material layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable.

FIELD OF THE INVENTION

The field of the invention relates to asphalt spray paving.

SUMMARY

Embodiments of the present invention are defined by the claims below,not this summary. This summary merely presents a high-level overview ofvarious aspects of the invention and a selection of concepts that arefurther described below in the detailed description section. Thissummary is not intended to identify key or essential features of theclaimed subject matter, nor is it intended to be used as an aid inisolation to determine the scope of the claimed subject matter. Thescope of the invention is defined by the claims.

In a first aspect, a paving mixture for application to a road surface isprovided, in accordance with an embodiment of the present invention. Themixture comprises a binding material layer applied to the surface toform a base layer on the surface, and an aggregate material layerapplied on top of the binding material layer. The binding material layercomprises at least 15% of the bitumen in the paving mixture by weight.The aggregate material layer contains a mixture of aggregate and bitumenthat provides a road surface. When constructed the paving mixture can be1 inch thick or greater.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Illustrative embodiments of the present invention are described indetail below with reference to the attached drawing figures, wherein:

FIG. 1 depicts a paving mixture applied to a surface, in accordance withan embodiment of the present invention;

FIG. 2 depicts a first method of applying a paving mixture to a surface,in accordance with an aspect of the present invention; and

FIG. 3 depicts a second method of applying a paving mixture to asurface, in accordance with an aspect of the present invention.

DETAILED DESCRIPTION

The subject matter of the various embodiments of the present inventionis described with specificity in this disclosure to meet statutoryrequirements. However, the description is not intended to limit thescope of claims. Rather, the claimed subject matter may be embodied invarious other ways to include different features, components, elements,combinations, and steps, similar to the ones described in this document,and in conjunction with other present and future technologies. Termsshould not be interpreted as implying any particular order among orbetween various steps disclosed herein unless the stated order of stepsis explicitly required. Many different arrangements of the variouscomponents depicted, as well as use of components not shown, arepossible without departing from the scope of the claims below.

In one aspect, a paving mixture for application to a surface isprovided. The mixture comprises a binding material layer that is appliedto the surface to form a base layer on the surface. An aggregatematerial layer is then applied on top of the binding material layer, thebinding and aggregate layers mixing to form a solid surface resistant tocracking and deformation. The binding material layer comprises at least15% of the bitumen within the paving mixture by weight. The aggregatematerial layer contains an asphalt mixture of bitumen and aggregate thatprovides a road surface. The aggregate material layer and the bindingmaterial layer can be combined on the surface within 30 seconds ofapplication of the binding material layer to allow for adequate mixingof the layers and prevent undesired diffusion of the binding materiallayer on the surface.

The paving mixture described herein can be used with any number ofsurfaces to provide an even, strong, water impermeable layer that isresistant to erosion and cracking. Surfaces to which the paving mixturemay be applied include roads, streets, interstates, parking lots,airport runways, and other similar surfaces. For simplicity, all ofthese surfaces are described as “road surfaces” herein. These surfacesdo not need to be a particular consistency, composition, or texture. Thebinding material layer combines with the aggregate material layer togive it elasticity, strength, and cohesion. The binding material layeralso fills in cracks on the surface to which the paving mixture isapplied. The aggregate material provides a firm structural componentthat will resist deformation.

The binding material layer provides a moisture barrier that preventscracks under the applied paving mixture from deteriorating or expanding.Additionally, the combination of a binding layer and an aggregate layerprovides a surface with a degree of elasticity that will resistcracking, molding, rutting, or similar deformation or damage, due to thebinding layer providing a dynamic element to the aggregate material. Inthis regard, the binding material fills in the space, or gaps, betweenaggregate materials, providing a more consistent aggregate base materialthat has less air gaps and more cohesion.

The binding material may form a certain percentage of the overallbitumen in the paving mixture to provide adequate adhesion of theaggregate elements and proper dispersion of the binding material intothe cracks on the surface. The amount of binding material used in thepaving mixture may vary based on the desired performance and adhesion ofthe aggregate material. An ideal percentage of the binding material isat least 15% of the bitumen in the paving mixture by weight, whichprovides sufficient bonding and elasticity, while maintaining structuralintegrity from the aggregate material. The binding material may containbitumen and other materials that form asphalt or similar surface formingmaterials, including sand, polymers, cross-linking agents, vulcanizationagents, accelerators, extenders, and fluxing agents. The bindingmaterial may also form a polymer modified asphalt emulsion (PMAE) orhot-asphalt cement, a petroleum solvent cutback asphalt, and othersimilar or analogous compositions. The viscosity of the binding materiallayer may be varied with the addition of different materials or heat.Varying the viscosity provides different diffusion properties of thebinding material across the surface to which it is applied, which may bedesirable based on the amount of wear of the surface or the texturalirregularities of the surface.

Heating the binding material decreases the viscosity, and helps toincrease penetration of the binding material into cracks on the surface.Heating the binding material and/or aggregate material also helps toincrease mixing of the binding material and the aggregate material oncethe layers are combined, providing a more uniform, durable pavingmixture. When a liquid asphalt emulsion is used as the binding material,the asphalt emulsion may be formulated to have a low viscosity to helpthe binding material (i.e., asphalt emulsion) penetrate throughout theaggregate mixture, coating a higher percentage of the aggregate materialin the aggregate material layer.

The aggregate material layer provides a structural component withcompressive strength and durability. The aggregate material may comprisesand, gravel, crushed stone, slag, rock dust, and the like. Theaggregate material may also include small or micro sized aggregatematerials, or rather a pulverulent material, to provide a more denselypacked or organized paving mixture. Exemplary pulverulent materials mayinclude fine sand or dust, which enhance the consistency of the pavingmixture by better distributing the aggregate materials throughout thepaving mixture. This also allows the aggregate material to mix with thebinding material more effectively, and reduces air gaps in the pavingmixture. In addition to the materials listed, the aggregate material mayinclude a synthetic aggregate.

An asphalt solution comprising bitumen may be added to the aggregatemixture. The asphalt solution may be the same as or similar to thebinding material, providing an adhesive or bonding element in theaggregate material layer. By including the asphalt solution, or bindingelement, in the aggregate mix, there is also enhanced bonding betweenthe aggregate materials prior to distribution over the binding materiallayer. A pulverulent material, such as sand or fine rock dust, may beadded to the asphalt mix to help control the diffusion of the asphaltmix during application when the aggregate particles are otherwise large.Larger aggregate particles are desirable for structural support reasons,but may allow an asphalt mix to spread or run too quickly when theaggregate is applied to the surface. The asphalt solution or asphaltmixture may further comprise a bituminous material comprising at leastone of asphalt cement, pitch, coal tar, vacuum tower bottoms, resin,performance grade asphalts, flux, and petroleum based products. Theasphalt solution can include antistrip and other additives, includingthose that prevent excessive running or dispersion of the asphaltsolution. The asphalt solution may comprise less than 15%, such as 5%,of the aggregate material layer. Additionally, the asphalt contained inthe aggregate mixture may coat some or all of the aggregate particles inthe mixture to create a Hot Mix Asphalt (HMA), which may be appropriatein circumstances that require a high amount of diffusion of the bindingmaterial. An aggregate mixture is considered a HMA asphalt when thetemperature of the aggregate mixture is at least 230 degrees Fahrenheit.A HMA provides increased distribution and uniformity of the bindingmaterial amongst the aggregate material in the aggregate material layer,due to the heat. A Warm Mix Asphalt (WMA) may also be used for similarpurposes. An asphalt mix is considered a WMA when the asphalt is heatedto at least 100 degrees Fahrenheit. A Cold Mix Asphalt (CMA) may also beused where the asphalt is approximately ambient temperature, and noenhanced diffusion of the binding material is desired. The type ofasphalt used, and the heat applied, may be determined based on ambientconditions and the desired diffusion or mixing of the binding andaggregate materials, prior to any compaction.

The portion of the paving mixture that comprises the binding material orasphalt solution may be varied based on the amount of adhesion needed toallow the paving mixture to withstand wear, movement, deformation,and/or cracking. In a preferred embodiment, the binding material may beat least 15% of the paving mixture by weight. Additionally, theaggregate material may be applied such that the paving mixture forms alayer at least 1 inch thick or greater after application, and/orcompaction, for example 1.25 inches, 1.5 inches, 2 inches, 3 inches, or4 inches.

The amount of binding material applied to the surface depends on thedesired amount of surface treatment, and the desired thickness of thepaving mixture product. In one embodiment, a distribution of 0.02gallons/ft² 0.03 gallons/ft² 0.04 gallons/ft² of binding material may beapplied to the surface. In another embodiment, a distribution of 0.05gallons/ft² of binding material may be applied to the surface. In yetanother embodiment, a distribution of 0.06 gallons/ft² of bindingmaterial may be applied to the surface. The depth of the aggregatematerial layer may be two or more times the depth of the bindingmaterial layer. This provides a stable surface and allows varyingdegrees of mixture between the binding material and the aggregatematerial, depending on the desired structural characteristics of thepaving mixture.

The aggregate material may be applied to the binding material layerwithin a relatively short amount of time so that the binding materialdoes not become too dispersed or diffuse on the surface afterapplication. This time period may be less than 30 seconds, and even asshort as a few seconds. As the aggregate material layer is applied tothe binding material layer, the layers may be compacted into a tighter,more uniform layer of paving mixture, removing air gaps. This compactingcan be accomplished mechanically, such as with a roller, pressingdevice, and/or machine. Compacting the binding layer and the aggregatelayer together provides an even, uniform paving surface and also helpsto distribute the binding material amongst the aggregate, providing amore stable, even paving mixture on the surface to which the pavingmixture is applied.

In another aspect, a method for application of a paving mixture to asurface is provided. The method comprises applying a binding materiallayer to the surface to form a base layer on the surface, and applyingan aggregate material layer on top of the binding material layer,wherein the binding material layer comprises at least 15% of the bitumenin the paving mixture by weight, the aggregate material layer containsan asphalt mixture that provides a road surface, and the aggregatematerial layer and the binding material layer are combined on thesurface within 30 seconds of application of the binding material layer.

The paving mixture may be applied by a vehicle that contains a bindingmaterial application component and an aggregate material applicationcomponent. The binding material application component may apply thebinding material layer ahead of the aggregate material layer, such as byspray paving, and may heat the binding material to a temperature thatprovides the desired viscosity or fluid properties. The aggregatematerial application component may apply the aggregate material on topof the binding material layer within 30 seconds or less of the bindingmaterial layer being applied to the surface. The aggregate materialapplication component may also heat the aggregate material. The bindingand aggregate layers may subsequently be compressed or compacted by aroller or a pressure application component. The binding material layermay comprise 15% or more of the bitumen in the paving mixture by weight,in a desired aspect.

In another aspect, a method for applying a paving mixture to a surfaceis provided, in accordance with an embodiment of the present invention.The method comprises applying a binding material layer to the surface toform a base layer on the surface, applying an aggregate material layeron top of the binding material layer, and compacting the bindingmaterial layer and the aggregate material layer together, wherein thebinding material layer comprises at least 15% of the bitumen in thepaving mixture by weight, the aggregate material layer contains anasphalt mixture that provides a road surface, and the aggregate materiallayer and the binding material layer are combined on the surface within30 seconds of application of the binding material layer. As discussedherein, compacting of the binding material layer and the aggregatematerial layer may be accomplished using a roller machine or amechanical compaction apparatus.

Referring to FIG. 1, an exemplary paving mixture applied to a surface isshown, in accordance with an embodiment of the present invention. InFIG. 1, a surface 108 is depicted with a paving mixture 100 applied ontop of the surface 108 with an even distribution, which may result aftermechanical compaction of the paving mixture 100. The paving mixture 100includes a binding material layer 102 proximate to the surface 108, andan aggregate material layer 104 applied on top of the binding materiallayer 102. The paving mixture 100 has a thickness 106 of 1.25 inchesafter application and/or after compaction of the layers.

Referring to FIG. 2, a flowchart of a first exemplary method 200 ofapplying a paving mixture to a surface is provided, in accordance withan aspect of the present invention. In FIG. 2, at a first step 202, abinding material layer is applied to a surface to form a base layer onthe surface. At a second step 204, an aggregate material layer isapplied on top of the binding material layer, wherein the bindingmaterial layer comprises at least 15% of the bitumen in the pavingmixture by weight, the aggregate material layer contains an asphaltmixture that provides a road surface, and the aggregate material layerand the binding material layer are combined on the surface within 30seconds of application of the binding material layer.

Referring to FIG. 3, a second exemplary method 300 of applying a pavingmixture to a surface is provided, in accordance with an aspect of thepresent invention. In FIG. 3, at a first step 302, a binding materiallayer is applied to a surface to form a base layer on the surface. At asecond step 304, an aggregate material layer is applied on top of thebinding material layer. At a third step 306, the binding material layerand the aggregate material layer are compacted, wherein the bindingmaterial layer comprises at least 15% of the bitumen in the pavingmixture by weight, the aggregate material layer contains an asphaltmixture that provides a road surface, and the aggregate material layerand the binding material layer are combined on the surface within 30seconds of application of the binding material layer.

Embodiments of the technology have been described to be illustrativerather than restrictive. Alternative embodiments will become apparent toreaders of this disclosure. Further, alternative means of implementingthe aforementioned elements and steps can be used without departing fromthe scope of the claims below, as would be understood by one havingordinary skill in the art. Certain features and subcombinations are ofutility and may be employed without reference to other features andsubcombinations, and are contemplated as within the scope of the claims.

The invention claimed is:
 1. A paving mixture for a road surface, themixture comprising: a bitumen binding material layer used to form a baselayer on the road surface; and an aggregate material layer applied ontop of the bitumen binding material layer, wherein the bitumen bindingmaterial layer comprises at least 15% of total bitumen in the pavingmixture by weight and the binding material layer is greater than ¼ inchthick after application, wherein the aggregate material layer comprisesa mixture of aggregate and bitumen that provides a road surface andwherein the aggregate and bitumen are mixed prior to application to thebitumen binding material, and wherein the paving mixture is at least 1inch thick after application.
 2. The mixture of claim 1, wherein thepaving mixture comprises a non-slag synthetic aggregate.
 3. The mixtureof claim 1, wherein the binding material layer and the aggregatematerial layer have been heated to at least 100 degrees Fahrenheit atthe time of application.
 4. The mixture of claim 1, wherein the bindingmaterial layer and the aggregate material layer have been heated to atleast 230 degrees Fahrenheit at the time of application.
 5. The mixtureof claim 1, wherein at least a portion of the aggregate material layercomprises a non-slag synthetic aggregate.
 6. The mixture of claim 1,wherein the aggregate includes at least one material selected from thegroup consisting of sand, gravel, crushed stone, slag, and rock dust. 7.The mixture of claim 1, wherein the binding material layer is applied inan amount of at least 0.02 gallons/ft² on the road surface.
 8. Themixture of claim 1, wherein the bitumen comprises less than 15% of theaggregate material layer by weight.
 9. A method of applying a pavingmixture to a surface, the method comprising: applying a bitumen bindingmaterial layer to the surface to form a base layer on the surface at arate of 0.02 gallons/ft²; and applying an aggregate material layer ontop of the binding material layer, wherein the aggregate material layercomprises a mixture of aggregate, pulverulent material, and bitumen thatprovides a road surface and wherein the aggregate, pulverulent materialand bitumen are mixed prior to application to the bitumen bindingmaterial, and wherein the bitumen binding material layer comprises atleast 15% of total bitumen in the paving mixture by weight and thebitumen binding material layer is greater than ¼ inch thick afterapplication.
 10. The method of claim 9, further comprising heating thebinding material layer and the aggregate material layer to at least 100degrees Fahrenheit prior to application.
 11. The method of claim 9,further comprising heating the binding material layer to at least 230degrees Fahrenheit prior to application.
 12. The method of claim 9,wherein the paving mixture is at least 1 inch thick after application.13. The method of claim 9, wherein the aggregate includes at least oneof gravel, crushed stone, and slag.
 14. The method of claim 9, whereinat least a portion of the aggregate comprises a non-slag syntheticaggregate.
 15. The method of claim 9, wherein the aggregate materiallayer and the binding material layer are combined on the surface withinat least 5 seconds of each other.
 16. The method of claim 9, wherein theaggregate material layer and the binding material layer are combined onthe surface within at least 10 seconds of each other.
 17. The method ofclaim 9, wherein the aggregate material layer and the binding materiallayer are combined on the surface within at least 15 seconds of eachother.
 18. A method for applying a paving mixture to a surface, themethod comprising: applying a bitumen binding material layer to thesurface to form a base layer on the surface; applying an aggregatematerial layer on top of the bitumen binding material layer; andcompacting the bitumen binding material layer and the aggregate materiallayer together, wherein the bitumen binding material layer comprises atleast 15% of total bitumen in the paving mixture by weight, wherein theaggregate material layer comprises a mixture of aggregate, pulverulentmaterial, and bitumen that provides a road surface and wherein theaggregate, pulverulent material and bitumen are mixed prior toapplication to the bitumen binding material, and wherein the aggregatematerial layer and the bitumen binding material layer are combined onthe surface within 5 to 30 seconds of application of the bindingmaterial layer.